Income Taxes (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended	6 Months Ended
Sep. 30, 2011	Sep. 30, 2010	Sep. 30, 2011	Sep. 30, 2010
Income Taxes (Textuals) [Abstract]
Income tax expense	$ 41.5	$ 12.0	$ 59.3	$ 21.8
Effective tax rate	26.60%	8.30%	22.00%	8.80%
United States federal statutory rate			35.00%
Overall effect of foreign tax rates on effective tax rate	6.70%	13.30%	8.90%	12.20%
Prior years' impact of discrete net tax benefits on effective tax rate	0.00%	12.50%	2.30%	13.00%
Discrete tax benefits associated with tax authority settlement	$ 0	$ 18.0	$ 6.2	$ 32.0

Income Taxes.

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- Definition

A ratio calculated by dividing the reported amount of income tax expense attributable to continuing operations for the period by GAAP-basis pretax income from continuing operations.

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- Definition

The domestic federal statutory tax rate applicable under enacted tax laws to the Company's pretax income from continuing operations for the period. The "statutory" tax rate is the regular tax rate if there are alternative tax systems.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef

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- Definition

The portion of the difference between the effective income tax rate and domestic federal statutory income tax rate that can be explained by the difference between statutory income tax rates in foreign jurisdictions and the domestic federal statutory income tax rate recorded during the period.

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The sum of the differences between the effective income tax rate and domestic federal statutory income tax rate attributable to all income tax settlements during the period.

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The sum of the current income tax expense or benefit and the deferred income tax expense or benefit pertaining to continuing operations.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef

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-Name Accounting Standards Codification

-Glossary Income Tax Expense (or Benefit)

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The sum of the differences between total income tax expense or benefit as reported in the Income Statement and the expected income tax expense or benefit computed by applying the domestic federal statutory income tax rates to pretax income from continuing operations attributable to all income tax settlements for the period.

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